<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <button>按钮</button>
    <input type="text" value="输入内容" />
    <script>
      var button = document.querySelector("button");
      var input = document.querySelector("input");
      button.onclick = function () {
        input.value = "niu bi";
        // button.disabled = "true"; //禁用按钮
        this.disabled = "true"; //this指向函数的调用者
      };
    </script>
  </body>
</html>
